INFLUENCE OF TOOL ROTATIONAL SPEED ON MECHANICAL AND MICROSTRUCTURAL PROPERTIS OF FRICTION STIR WELDING OF HIGH STRENGTH LOW ALLOY STEEL JOINTS
Keywords:Friction stir welding, HSLA steel, Tool rotational speed, Microstructure, Tensile properties
Naval grade high strength low alloy (HSLA) steel plates were welded using friction stir welding (FSW) process with five different tool rotational speeds varying from 500 rpm to 700 rpm to study the effect of tool rotational speed on FSW joint characteristics. Microstructural characteristics of the weld joints were analyzed using optical microscopy (OM). Of the five tool rotational speed, the tool rotational speed of 600 rpm yielded defect free sound joint with acceptable impact toughness properties. Tensile strength and hardness of the stir zone are higher (overmatched) compared to that of the base metal due to the formation of finer grains with high dislocation density caused by the stirring action of the rotating tool.
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